Question

The triad of the nuclei that is isotonic is:

• A. ${}_6{N}^{14}{,}_7{N}^{14}{,}_9{F}^{19}$
• B. ${}_6{C}^{14}{,}_7{N}^{15}{,}_9{F}^{17}$
• C. ${}_6{C}^{14}{,}_7{N}^{14}{,}_9{F}^{17}$
• D. ${}_6{C}^{12}{,}_7{N}^{14}{,}_9{F}^{19}$

Answer 1

Answer: (B)

${}_6{C}^{14}{,}_7{N}^{15}{,}_9{F}^{17}$

Isotonic species are defined as the species which have the same number of neutrons.

No. of neutrons in:

${}_6{C}^{14}=14-6=8$

${}_7{N}^{14}=14-7=7$

${}_9{F}^{19}=19-9=10$

${}_7{N}^{15}=15-7=8$

${}_9{F}^{17}=15-7=8$

${}_6{C}^{12}=12-6=6$

${}_6{C}^{14},{}_7{N}^{15},{}_9{F}^{17}$ are isotonic species.

Hence, option B is correct.